In the Rochester area, you'll find plenty of crappie in the Seneca River, especially at night. There's a guy at this forum who fishes Seneca almost exclusively, and he slams the slabs at night from June through september.
Also, there's lots of slabs cruising around in Canadaigua and Honeoye Lakes. Both lakes have what can be called better than average crappie fishing -- in terms of numbers and size.
You'll need to get out in a boat -- but that shouldn't be a problem -- both lakes rent them .... small rowboats with (I believe0 10 hp motors.
Bring plenty of fathead minnows, and fish the drop-offs and weedlines, in 12 to 20 feet of water.
You can also throw 1/8 oz. jigs, with twister tail grubs, in white, chartreuse,
pumpkin, and watermelon --- and any combination thereof.
There are numerous smaller lakes and ponds scattered arouind the Rochester area -- get a good topo map, and make some phone calls.
You'll only catch big crappies in lakes that are KNOWN to hold big crappies -- otherwise, you'll be wasting your time !
Hope this helps.
Good luck to you -- and tight lines !
Kaptain K.